class Control {
    private state: string;
    // state: string;
    userName: string;

    constructor() {
        this.state = "state";
        this.userName = "userName";
    }
}

interface SelectableControl extends Control {
    select(): void;
}

class Button  extends  Control implements SelectableControl {
    userName: string;
    // private state: string;
    select() {
        console.log("button select");
    }
}

const button = new Button();
button.select();
console.log(button.userName)
